This invention relates to gramophone equipment and is particularly concerned with a record player having a turntable and a tone arm and comprising record track selection means including selector means for manually selecting a track, sensing means for scanning a record on said turntable to determine its reflectivity thereby to locate the bands of relatively low groove density between recorded tracks of the record and processing circuitry for processing the signal from the sensing means. Such equipment is described in U.K. Patent Application No. 13084/75 and Stimmler U.S. Specification No. 2952464.
In such systems, it has been found that the reflectivity of records varies considerably from record to record and, particularly in high quality records, across individual tracks of a single record. Thus, equipment with a signal threshold and gain for adequately detecting signal peaks produced by bands between tracks of a low quality record can give a false detection with a higher quality record, in which groove density can fall within a track to give a reflectivity of the same order as that occurring in a band of a low quality record. If, on the other hand, one manually adjusts the threshold or gain between records, this problem can be overcome although it is an inconvenient solution and one which is particularly disadvantageous will autochangers.
An object of the present invention is to provide equipment in which the threshold or gain is automatically adjusted to take individual record characteristics into account.